LBaaS: check for associations before deleting health monitor

Need to prohibit health monitor deletion if it has associations with
pools. Given that pools may belong to different lbaas drivers the process
of monitor deletion becomes complex and unreliable since association
deletion may fail on any single driver.

DocImpact

Closes-Bug: #1243129
Change-Id: I27c20e7a5be8433f90569534ecf838e33027cb00

neutron/db/loadbalancer/loadbalancer_db.py

@@ -770,6 +770,15 @@ class LoadBalancerPluginDb(LoadBalancerPluginBase,
         return self._make_health_monitor_dict(monitor_db)
 
     def delete_health_monitor(self, context, id):
+        """Delete health monitor object from DB
+
+        Raises an error if the monitor has associations with pools
+        """
+        query = self._model_query(context, PoolMonitorAssociation)
+        has_associations = query.filter_by(monitor_id=id).first()
+        if has_associations:
+            raise loadbalancer.HealthMonitorInUse(monitor_id=id)
+
         with context.session.begin(subtransactions=True):
             monitor_db = self._get_resource(context, HealthMonitor, id)
             context.session.delete(monitor_db)

neutron/extensions/loadbalancer.py

@@ -69,6 +69,11 @@ class PoolInUse(qexception.InUse):
     message = _("Pool %(pool_id)s is still in use")
 
 
+class HealthMonitorInUse(qexception.InUse):
+    message = _("Health monitor %(monitor_id)s still has associations with "
+                "pools")
+
+
 class PoolStatsNotFound(qexception.NotFound):
     message = _("Statistics of Pool %(pool_id)s could not be found")
 

neutron/services/loadbalancer/plugin.py

@@ -254,19 +254,6 @@ class LoadBalancerPlugin(ldb.LoadBalancerPluginDb,
     def _delete_db_health_monitor(self, context, id):
         super(LoadBalancerPlugin, self).delete_health_monitor(context, id)
 
-    def delete_health_monitor(self, context, id):
-        with context.session.begin(subtransactions=True):
-            hm = self.get_health_monitor(context, id)
-            qry = context.session.query(
-                ldb.PoolMonitorAssociation
-            ).filter_by(monitor_id=id).join(ldb.Pool)
-            for assoc in qry:
-                driver = self._get_driver_for_pool(context, assoc['pool_id'])
-                driver.delete_pool_health_monitor(context,
-                                                  hm,
-                                                  assoc['pool_id'])
-        super(LoadBalancerPlugin, self).delete_health_monitor(context, id)
-
     def create_pool_health_monitor(self, context, health_monitor, pool_id):
         retval = super(LoadBalancerPlugin, self).create_pool_health_monitor(
             context,

neutron/tests/unit/db/loadbalancer/test_db_loadbalancer.py

@@ -1022,8 +1022,8 @@ class TestLoadBalancer(LoadBalancerPluginDbTestCase):
             qry = qry.filter_by(id=monitor['health_monitor']['id'])
             self.assertIsNone(qry.first())
 
-    def test_delete_healthmonitor_cascade_deletion_of_associations(self):
-        with self.health_monitor(type='HTTP', no_delete=True) as monitor:
+    def test_delete_healthmonitor_with_associations_raises(self):
+        with self.health_monitor(type='HTTP') as monitor:
             with self.pool() as pool:
                 data = {
                     'health_monitor': {
@@ -1046,17 +1046,21 @@ class TestLoadBalancer(LoadBalancerPluginDbTestCase):
                 qry = ctx.session.query(ldb.PoolMonitorAssociation)
                 qry = qry.filter_by(monitor_id=monitor['health_monitor']['id'])
                 self.assertTrue(qry.all())
-                # delete the HealthMonitor instance
+                # try to delete the HealthMonitor instance
                 req = self.new_delete_request(
                     'health_monitors',
                     monitor['health_monitor']['id']
                 )
                 res = req.get_response(self.ext_api)
-                self.assertEqual(res.status_int, webob.exc.HTTPNoContent.code)
-                # check if all corresponding Pool associations are deleted
+                self.assertEqual(res.status_int, webob.exc.HTTPConflict.code)
+
+                qry = ctx.session.query(ldb.HealthMonitor)
+                qry = qry.filter_by(id=monitor['health_monitor']['id'])
+                self.assertIsNotNone(qry.first())
+                # check if all corresponding Pool associations are not deleted
                 qry = ctx.session.query(ldb.PoolMonitorAssociation)
                 qry = qry.filter_by(monitor_id=monitor['health_monitor']['id'])
-                self.assertFalse(qry.all())
+                self.assertTrue(qry.all())
 
     def test_show_healthmonitor(self):
         with self.health_monitor() as monitor:
@@ -1363,6 +1367,15 @@ class TestLoadBalancer(LoadBalancerPluginDbTestCase):
                                  pool_updated['pool']['id'])
 
                 # clean up
+                # disassociate the health_monitor from the pool first
+                req = self.new_delete_request(
+                    "pools",
+                    fmt=self.fmt,
+                    id=pool['pool']['id'],
+                    subresource="health_monitors",
+                    sub_id=health_monitor['health_monitor']['id'])
+                res = req.get_response(self.ext_api)
+                self.assertEqual(res.status_int, webob.exc.HTTPNoContent.code)
                 self._delete('health_monitors',
                              health_monitor['health_monitor']['id'])
                 self._delete('members', member1['member']['id'])
@@ -1370,10 +1383,10 @@ class TestLoadBalancer(LoadBalancerPluginDbTestCase):
 
     def test_create_pool_health_monitor(self):
         with contextlib.nested(
-            self.pool(name="pool"),
             self.health_monitor(),
-            self.health_monitor()
-        ) as (pool, health_mon1, health_mon2):
+            self.health_monitor(),
+            self.pool(name="pool")
+        ) as (health_mon1, health_mon2, pool):
                 res = self.plugin.create_pool_health_monitor(
                     context.get_admin_context(),
                     health_mon1, pool['pool']['id']
@@ -1401,9 +1414,9 @@ class TestLoadBalancer(LoadBalancerPluginDbTestCase):
         with mock.patch.object(self.plugin.drivers['lbaas'],
                                'create_pool_health_monitor') as driver_call:
             with contextlib.nested(
-                self.pool(),
-                self.health_monitor()
-            ) as (pool, hm):
+                self.health_monitor(),
+                self.pool()
+            ) as (hm, pool):
                 data = {'health_monitor': {
                         'id': hm['health_monitor']['id'],
                         'tenant_id': self._tenant_id}}
@@ -1420,10 +1433,10 @@ class TestLoadBalancer(LoadBalancerPluginDbTestCase):
 
     def test_pool_monitor_list_of_pools(self):
         with contextlib.nested(
+            self.health_monitor(),
             self.pool(),
-                self.pool(),
-                self.health_monitor()
-        ) as (p1, p2, hm):
+            self.pool()
+        ) as (hm, p1, p2):
             ctx = context.get_admin_context()
             data = {'health_monitor': {
                     'id': hm['health_monitor']['id'],
@@ -1455,9 +1468,9 @@ class TestLoadBalancer(LoadBalancerPluginDbTestCase):
 
     def test_create_pool_health_monitor_already_associated(self):
         with contextlib.nested(
-            self.pool(name="pool"),
             self.health_monitor(),
-        ) as (pool, hm):
+            self.pool(name="pool")
+        ) as (hm, pool):
             res = self.plugin.create_pool_health_monitor(
                 context.get_admin_context(),
                 hm, pool['pool']['id']
@@ -1501,8 +1514,10 @@ class TestLoadBalancer(LoadBalancerPluginDbTestCase):
             self.assertFalse(updated_pool['status_description'])
 
     def test_update_pool_health_monitor(self):
-        with self.pool() as pool:
-            with self.health_monitor() as hm:
+        with contextlib.nested(
+            self.health_monitor(),
+            self.pool(name="pool")
+        ) as (hm, pool):
             res = self.plugin.create_pool_health_monitor(
                 context.get_admin_context(),
                 hm, pool['pool']['id'])

neutron/tests/unit/services/loadbalancer/drivers/test_agent_driver_base.py

@@ -282,9 +282,9 @@ class TestLoadBalancerCallbacks(TestLoadBalancerPluginBase):
                     self.assertEqual([member], logical_config['members'])
 
     def test_get_logical_device_pending_create_health_monitor(self):
+        with self.health_monitor() as monitor:
             with self.pool() as pool:
                 with self.vip(pool=pool) as vip:
-                with self.health_monitor() as monitor:
                     ctx = context.get_admin_context()
                     self.plugin_instance.update_status(ctx, ldb.Pool,
                                                        pool['pool']['id'],
@@ -408,9 +408,9 @@ class TestLoadBalancerCallbacks(TestLoadBalancerPluginBase):
 
     def test_update_status_health_monitor(self):
         with contextlib.nested(
-            self.pool(),
-            self.health_monitor()
-        ) as (pool, hm):
+            self.health_monitor(),
+            self.pool()
+        ) as (hm, pool):
             pool_id = pool['pool']['id']
             ctx = context.get_admin_context()
             self.plugin_instance.create_pool_health_monitor(ctx, hm, pool_id)
@@ -671,9 +671,9 @@ class TestLoadBalancerPluginNotificationWrapper(TestLoadBalancerPluginBase):
 
     def test_create_pool_health_monitor(self):
         with contextlib.nested(
+            self.health_monitor(),
             self.pool(),
-            self.health_monitor()
-        ) as (pool, hm):
+        ) as (hm, pool):
             pool_id = pool['pool']['id']
             ctx = context.get_admin_context()
             self.plugin_instance.create_pool_health_monitor(ctx, hm, pool_id)